The Mother of All Hoods

To: Aquatic-Plants at actwin_com
Subject: The Mother of All Hoods
From: steveb at bga_com (Steve Benz)
Date: Wed, 23 Oct 1996 01:31:52 -0500

I just finished building a hood for my 45 gal.  (36"l 18"w 16"tall).
It's design is an elaboration on George Booth's hood design in the
Krib.  I thought I'd post a note about it for anyone thinking about
building a hood.

My modifications were as follows:

 -  It's hot here, so having the ballast in the hood is a no-go.
    (too much heat build-up).  In spite of what you might read,
    the ballast can be located anywhere, but with non-T8 bulbs,
    you need to put the bulb within 3/4" of a grounded surface.
    A strip of aluminum will fit the bill.
 -  It's hot here - I put in some fans to pull air through the
    hood.
 -  George has some space behind his aquarium, so when he really
    needs to root around, he folds it up once and pushes it back
    some.  I didn't have that option, so instead, I made my hood
    so that it has two folding joints, giving me 4 folding options,
    crudely diagrammed below (++ really indicates a single hinge,
    folded 180 degrees.)

                                      ++          o  o
                             |o      o||o        --+--+
        --+--+--        --+--+       --+            --+
         o  o  o         o  o         o              o
       (fully closed) (3" access) (8" access) (12" access)

 -  On George's hood, he has to go through the UNSPEAKABLE BOTHER
    of hitting a switch to avoid being blinded when he flips the
    hood up.  Being a CERTIFIED ELECTRONICS GENIUS, I wired up
    some switches in the hood itself so that when you open the hood,
    the power to the appropriate ballast is cut.


Lessons learned:

I could have saved myself some time if I had more carefully planned
out my wiring.

The switches in the hood to cut power when you flip up the hood are
staggeringly easy to achieve.  I highly recommend it to anyone building
a new hood.

To be avoided at all costs are exposed hot wires in your hood.  I
minimized this by making sure that no hot wires were spliced inside
the hood, and the switches inside the hood are all switching the
ground wire.

Also, I put on a little control panel onto the hood so that you can
turn the fans on and off, override the timer, and turn off banks of
lights.  It's a really easy thing to do and really convenient.  I
recommend this too.  One other reason to do this is that the
control-panel box makes a nice, safe place to put spliced wires!

If you decide to put fans in your hood, don't be stupid like I was and
base your purchasing decision solely on the size and voltage requirements.
Your A-NUMBER-1-PRIMARY-REQUIREMENT ought to be how quiet the fans are!
Take it from ol' Steve who's got fans that are right up there with
vaccuum cleaners...  (But ooooh-dawwggies they blow some air!)

Varnish smells bad.  I put the last coat on a week ago and the darn thing
still stinks!  I've had the windows open and the fans blaring, hoping to
put a stop to it, but the odor continues. [[ I hope that stuff isn't too
hard on my fish... ]]

I saw some advice posted here about whether fans should blow into the
aquarium or out of it.  Someone suggested blowing air directly onto the
water would increase evaporation.  I fixed mine to blow air out - I
figure the primary mission here isn't to cool the tank by evaporation,
but rather to remove the heat from the lights.  For reasons that engineers
know and I don't, every computer fan I've ever seen blows air away from
the thing being cooled.  I've copied that design.  One thing I can report
is that with the fans turned on, the breeze causes definite ripples on
the surface of the water, so I can't help but think that blowing air out
is the most efficient way to decrease water temperature.

George used a piano hinge for his joint.  I just used your basic-regular-
old hinges.  They work fine.

One thing that wasn't immediately obvious to me was how to run wires
across the hinge.  You don't want to just run the wires straight across
the hinge because you'll have alot of excess wire when you close the
hinge, and that could cause problems.  The trick is to run the wires
*diagonally* across the hinge - that is, secure the bundle of wires
that crosses right against the hinge, but at least a foot apart (along
the length of the joint.)  When you close the hood, the wires still
sag, but only a little bit.  You can secure them with a spring to
complete the job, if you think you need to.  (But it's not so easy
to find one the right size and strength.)

As always: measure twice, cut once!

                                - Steve
------
Steve Benz (steveb at tall-tree_com)   |   Tall Tree Software Co.
http://www.tall-tree.com            |   Ph/Fax: 512-453-4909